Just a few years ago, the idea of electrically stimulating your brain in the comfort of your own home would have sounded pretty weird, and probably like a bad idea.

But the practice of brain-zapping—in particular, an easy-to-pull-off technique called transcranial direct current stimulation (tDCS)—has quickly advanced from labs to living rooms. DIYers are building their own devices and trading tips online, while startups are bringing out consumer products.

With that as the backdrop, a group of neuroscientists and manufacturers met in New York City on Sunday 28 August to discuss potential regulations for brain stimulation devices sold directly to consumers. “Neuromodulation is already here—it’s on Amazon, it’s in the coverage of the Olympics, it’s everywhere,” said conference organizer Marom Bikson, a professor at the City College of New York. “But there isn’t a cohesive message from scientists or industry about regulations. As a community, we’re behind.”

The group agreed on Sunday to suggest guidelines to the U.S. Food and Drug Administration (FDA), which sets rules for medical devices. The FDA has been discussing this possibility of regulating neurotech for at least two years, said James Giordano, chief of the neuroethics studies program and a professor of neurology at Georgetown University in Washington, D.C. “I’ve been part of those discussions,” Giordano said.

While tDCS isn’t the only type of noninvasive brain stimulation, it’s the simplest: The user just presses a couple of electrodes to the scalp to send a tiny amount of current through a specific region of the brain. The effects depend most obviously on where the electrodes are placed, but also on factors such as current amplitude, stimulation duration, and existing conditions in the user’s brain.

Neuroscientists are testing tDCS’s effects on every neural and psychological disorder you can imagine, and are also investigating its effects on cognition, emotion, and behavior. It’s fair to say it’s a hot topic of research: The chart at right, from the PubMed database, shows the number of papers published on tDCS over the years. In 1989, there were two such papers published; last year there were 608.

In Europe, tDCS was recently approved for depression and chronic pain. While the FDA has yet to follow suit and approve its use in the United States for any medical conditions, such a move seems inevitable. And since tDCS can be easily administered by a portable device, clinicians are already thinking about how at-home medical use could safely be permitted.

At the meeting on Sunday, several researchers explained how at-home clinical treatment could work: Physicians could control “dosage” by providing a unique keycode for each stimulation session that allows activation of the device, and could use Skype to supervise patients as they familiarized themselves with the gear. Researchers also stressed the need for standardized devices that position the electrodes properly on the user’s head.

But consumers using products they buy on Amazon need a different set of protections, Giordano told IEEE Spectrum in an interview.

Some of the first products that came on the market made inaccurate claims about their benefits, Giordano said. The manufacturers made statements based on scientific studies that used research-grade tDCS equipment under carefully controlled conditions. But the companies hadn’t carried out those same studies using their own products.

“That’s like saying, ‘A Maserati can go 200 miles per hour. The Maserati is a car, and I also make a car, and therefore my car goes 200 miles per hour,’” Giordano said. “Oh, and also, I’m not using my car on a racetrack, and I don’t have an experienced race car driver behind the wheel.” As a first step toward a responsible marketplace, Giordano said, manufacturers must be required to clearly define and support their claims, and to carefully communicate what their devices can and cannot do.

The group’s guidelines will also recommend that people with neural or psychiatric conditions consult their physicians before using any brain stimulating gadget. That category includes people with conditions like depression, anxiety, and addiction, who are already turning to DIY treatments using homemade or commercially available tDCS rigs.

Finally, they’ll recommend that neuromodulation devices not be used by children unless a physician explicitly recommends such use. There are too many unknowns regarding its effects on the developing brain, Giordano says.

Making claims about a commercial device for home use, based on scientific studies that used research-grade tDCS equipment under carefully controlled conditions, is like saying, “A Maserati can go 200 miles per hour. The Maserati is a car, and I also make a car, and therefore my car goes 200 miles per hour.”
—James Giordano, Georgetown University

Setting such regulations won’t stop people from doing whatever they want with devices. But then it becomes a matter of “buyer beware,” says Giordano. “We’ll tell you how to use something properly, and if you chose to deviate from that, that’s your choice,” he says. “Sears can sell a chain saw with perfectly good intentions that it only be used to cut wood, but some idiot is going to juggle it.”

The group that met on Sunday included representatives of a few companies that either sell a tDCS product now or intend to launch one soon. The speakers made the case that all manufacturers should get on board with these proposed regulations, because setting clear rules for their products’ use can protect them from lawsuits. But such widespread buy-in may be wishful thinking.

Giordano named two of the companies represented on Sunday as exemplars of what the field should aspire to: Halo, whose brain-stimulating gadget for athletes will soon go on sale, and Soterix, which sells tDCS units for medical and research use only. These companies, Giordano said, are doing their own research to back up their claims. “Those two companies are doing it right,” Giordano said. “The implication is that other companies are not doing it as well.”

Some companies claim not only that their devices treat disorders like depression, anxiety, addiction, and chronic pain, they also boast of improving cognition, memory, and social skills. Many DIYers seem most interested in these enhancement possibilities of tDCS.

That experimentation makes scientists nervous. In a recent open letter to DIY users, 43 leading academics pleaded with users to consider that neuroscientists are still trying to answer basic questions about how tDCS works, and that many safety issues remain unresolved. That letter noted that stimulation is not as targeted as many people assume; enhancing one cognitive function may come at the cost of others, and “whatever brain changes occur may be long-lasting—for better or worse.”